[Windows] Can save a `strlen` call knowing there's exactly one zero

[AlexGuteniev]

Not sure if it is really needed, as perf gain and simplification are both very small.

Referring to this:

stacktrace/include/boost/stacktrace/detail/frame_msvc.ipp

Lines 222 to 234 in 75b7986

	if (!res && size != 0) {
	result.resize(size);
	res = (S_OK == idebug_->GetNameByOffset(
	offset,
	&result[0],
	static_cast<ULONG>(result.size()),
	&size,
	0
	));
	trim_right_zeroes(result);
	} else if (res) {
	result = name;
	}

According to the updated IDebugSymbols::GetNameByOffset documentation, sizes will include the space for exactly one null terminator:

This size includes the space for the '\0' terminating character.

So the assignment in the else branch can be like:

result.assign(name, size - 1);

and trim_right_zeroes can be avoided by resizing string as result.resize(size - 1) prior the second call.

Ditto for GetLineByOffset below.

[apolukhin]

Done in 7c6778e

@AlexGuteniev note that the docs for GetLineByOffset() still have no This size includes the space for the '\0' terminating character., so I left the code as is for that call. The impact should be unnoticeable.

[AlexGuteniev]

@apolukhin, I did a bulk fix of these MicrosoftDocs/windows-driver-docs-ddi#1255 , but unfortunately missed this one 😕